As is known, such articles are obtained by superposing a sheet of permeable material (non-woven fabric) on a sheet of impermeable material, and interposing between them a section of padding comprising an absorbent pad.
In recent years, to increase the absorbency of such products, manufacturers have made a section of padding consisting of at least two superposed pads having different shapes and dimensions.
In general, a first pad, or inner pad, which is substantially rectangular, is positioned on a second supporting pad, or outer pad, which is larger, having a substantially hourglass anatomical shape.
Usually, both pads are made from a mixture consisting of cellulose pulp (fluff) and granules of superabsorbent polymers (SAP), In order to increase drainage of the liquid absorbed and to increase the concentration of the superabsorbent polymer in a precise zone of the section of padding, the inner pad is made thicker than the supporting pad, by superposing two or more layers of absorbent material containing a large quantity of granular superabsorbent material (SAP).
In a prior art machine for making a section of padding of the above-mentioned type, there is a first suction drum for forming and conveying the multi-layer inner pad and a second suction drum for forming and conveying the outer supporting pad, which consists of a single layer of absorbent material.
The first and second drums are side by side and rotate in opposite directions about respective axes which are parallel with each other. The two drums are substantially at a tangent to one another at a station where the multi-layer inner pad, conveyed by the first drum, is placed on the outer pad, conveyed by the second drum.
Then, the two superposed pads are conveyed towards compressing means to complete the production of the absorbent section of padding.
It has been noticed that the absorbent section of padding, made according to the prior art described, may not be suitably stuck together and compact, despite the above-mentioned compressing operation, since the granules of superabsorbent material (SAP), present in a large quantity in the layers which make up the multi-layer inner pad, do not allow the fibres of the cellulose pulp (fluff) to stably interpenetrate one another.
A lack of cohesion between the layers which make up the multi-layer pad results in dispersion in the environment of the granules of superabsorbent material (SAP), which, over time, may cause incorrect operation or faults in the mechanical devices for forming the pads.
Moreover, in the prior art referred to the absorbent section of padding may be unevenly compressed, since the compression occurs on superposed pads with different thicknesses.